(i) Technical Field
The present invention relates to a motor.
(ii) Related Art
There is known a motor including: a rotor; a stator arranged around the rotor. The rotor includes: a rotary shaft; a magnetic body fixed to the rotary shaft; and plural permanent magnets fixed on an outer circumference of the magnetic body. The stator includes: an iron core; and a coil for exciting the iron core. Such a magnetic body may have projections for positioning the permanent magnets. Such a projection is sandwiched between the adjacent permanent magnets. Japanese Patent Application Publication No. 8-65929 and Japanese Utility Model Application Publication No. 59-99686 disclose techniques relevant to such a motor.
Magnetic field lines have emanated from one of the adjacent permanent magnets may partially extend to the other thereof through the projection. Such magnetic field lines may not contribute to a magnetic attractive force or a magnetic repulsive force generated between the permanent magnets and the iron core. This may reduce the torque of the rotor.